Method of deasphaltizing oils



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K. A. FISCHER METHOD OF DEASPHALTIZING OILS Filed Nov. 15, 1949 April 8, 1952 Q\ IE W.KZCAQP BY Patented Apr. 8 1 952 UNITED STATES PATENT OFFICE METHOD OF DEAS-PHALTIZING OILS- Karl A. Fischer, College Park, Md.

Application November 15, 1949, Serial No. 127,477 6 Claims. (01. 196-14.45)

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

The invention relates to a new deasphaltizing agent and an improved process for deasphaltizing petroleum oils, distillation, residues, bituminous extracts and shale oil residues. More partieularly, this invention is concerned with deasphaltizing oils and oil stock residues with hexafiuoroxylene in an improved manner which facilitates and economizes oil production.

The oil components which remain in asphaltic residues are very desirable and valuable products. Likewise, the separation of asphalti'c-resinous materials from an oil with a minimum effort is of considerable importance in simplifying economical processing of petroleum products.

Experience in the art of processing petroleum has shown that there is considerable difference between asphaltic resinous and amorphous materials on the one hand, and parafiin crystalline or microcrystalline wax material on the other hand. Fundamentally, the process of the present invention concerns a separation of the asphaltic and resinous constituents from petroleum oils and distillation residues and the like by solvent extraction of the oil and crystalline wax material from the asphaltic-material-containing oil stock at moderately elevated temperatures, with removal of solvent by cooling, while retaining crystalline wax material, if present, in the oil phase.

Heretofore, the extraction of asphaltic or resinous components from petroleum residues, particularly for obtaining heavy oil stocks has been rather complicated; the only present commercial method being treatment with propane, a flammable substance, which is a gas at normal temperature and pressure. Other agents in the nature of alcohols, esters and a series of halogen containing organic liquids have been suggested without obtaining commercial success. In general, agents of the character of organic solvents, as above noted, which may be used in separating oils and asphaltic materials, create fire hazards, necessitate equipment which will withstand high pressure, and/or require during processing the input of considerable heat energies involving extreme temperature conditions.

It is therefore an object of my invention to provide an improvement in and simplification of the method of separating asphaltic-resinous constituents from oils.

Another object of my invention is to provide an improvement in a system or process for'extracting oils from petroleum residues and tars.

Another object of this invention is to improve the method of separating oils from petroleum residues containing the oil, by selective solvent precipitation with hexafiuoroxylene. I

An additional object of this invention is to provide an improved process of separating asphaltlc and oil constituents under conditions of particular selectivity at moderate temperature changes for an oil processing system.

A further object of this invention is to provide an improved selective solvent for separating asphaltic-resinous constituents from petroleum oils and distillation residues, and also improved solvent recovery.

Other objects, advantages and improvements provided will be apparent from. the following disclosure when considered in conjunction with the accompanying drawing wherein there is disclosed a diagrammatic illustrative deasphaltizing and solvent recovery system.

In the application of the hexafiuoroxylene to an asphaltic oil or residue, it was discovered that upon mixing an oil or residue stock with isomers of hexafluoroxylene, of commercial grade, in the proportions of from 100% to 300% or more on a volumetric basis, and preferably at double the volume of solvent to petroleum stock, the oil content of the residue at 30 C. absorbs only a portion of the hexafluoroxylene and at temperatures between C. and 120 C. the oil" and solvent appear to form a homogeneous liquid with the asphaltic-resinous constituents in a com pletely separate stage which can be removed from the liquid stage by decanting, centrifuging or filtering, as desirable. Thereafter cooling the oil-solvent mix to 30 C. resultsin a separation of approximately 50% and more of the solvent from the oil.

In the case of heavy California asphaltic 011 residue as an oil stock, to which is added a meta para-hexafluoro-xylene solvent mixture of com-- mercial grade, in the proportion of 100% per volume, there is an absorption of approximately 40% by volume of the hexafiuoroxylene, and the asphalt begins to appear in a separate and distinct phase. Upon gentle heating of the mixture to C., and upon holding the temperature between 65 C.and C. for a few minutes, the oil and solvent form a homogeneous liquid phase and the asphaltic-resinous constituents form a separate viscous or semi-solid phase. Separation between the liquid and semi-solid materials may be effected by conventional means, as heretofore indicated. When the separated oil-solvent mix is cooled to 30 C., approximately 50% to 55% of the solvent forms a separate clean cut phase containing very little oil, from which phase the oil containing approximately 45% of the solvent is separable by decanting or drainage as desired. The separated solvent is immediately available for further extraction of asphaltic-resinous constituents contained in a new petroleum batch stock.

In the oil product obtained by the above process, the solvent content, as indicated, is partially removed by the reduction of the temperature to 30 C. If chilling of the oil-solvent phase is carried to lower temperatures, say 0., only 15 %-20% of the solvent remains in the oil phase and the solvent phase contains less oil. Generally it is a question of heat economy and solvent recovery which determines the feasibility of chilling to low temperatures in any particular process. Extremely low temperatures in the oil phase generally requires a less heat input for evaporation of solvent from the oil in. the final stages of oil recovery. As a final step, for the above oil-solvent mix which still contains approximately 45% solvent, the oil is freed from solvent by evaporating of the solvent under vacuum to produce a heavy oil, free of asphaltic constituents and solvent.

As illustrated by the drawing, which shows what is in effect a continuous phase separation and solvent recovery system, a solvent receiving and storage container 10 supplies hexafluoroxylene through conduit ll, controlled by valve 1'2. through heater 13, containing a conventional heating coil 14, and by way of conduit l into a mixing and separating container l5. From container ll heated or stored petroleum oils and distillation or asphaltic residues are supplied in equal proportions or less, as heretofore indicated, to the mixing chamber 16 by way of conduit I8, controlled by valve l9, through heater 20, containing heater coil 2!, and thence through conduit 22. The solvent discharge conduit l5 and petroleum stock discharge 22 extend into container l6 for the purpose of discharging and mixing the residue and solvent at a point adjacent to the base of the container MS, as in most cases the asphaltic-resinous materials when separated will float on the surface of the liquid. In other instances where the semi-solids settle, the discharge ends of the conduits l5 and 22 may be positioned in container 16 as desired.

By means of heating coils I4 and 2!, or other suitable temperature conditioning means for the container 16, the oil solvent mix is heated to the temperature at which complete miscibility between the oil and solvent takes place to the exclusion of the asphaltic-resinous constituents of the mix. For the California residue this temperature appears to be on the order of 65 0., whereas for other oil stock and residue material the temperature will vary from about 60 C. to approximately 120 C. or slightly more, dependent upon the particular stock material used, whose characteristics will vary with different localities of origin.

As indicated, the solvent and oil at these higher temperatures become, for all practical purposes, a homogeneous liquid mix whichretains the crystalline wax or wax constituents in the solubl'e phase, and the asphaltic-resinous constituents in a separate viscous or semi-solid phase.

After the temperature of complete miscibility between the oil. and solvent has been reached and permitted to rise a few degrees or stand for a 4 few minutes to allow for complete separation or precipitation of the asphaltic-resinous constituents they are carried away by conduit 23, controlled by valve 24, to any suitable retainer (not shown). While it is apparent that separation of the liquid phase and precipitated phase may be accomplished by filtering or centrifuging, the arrangement, as illustrated, operates by displacement. The flows of solvent and oil stock material being introduced adjacent to the base of container l6, as heretofore indicated, the take-off 23 is accordingly positioned adjacent the top of container l5 or at the base of container [6 dependent upon the particular specific gravities of the separated semi-solids.

From the container [5 the substantially homogeneous mix of oil and solvent are conveyed by conduit 25, controlled by valve 26, into and through a liquid cooler 21, containing conventional cooling coil 23, and thence by conduit 29 into an oil solvent separating container 30. In the cooler 2'! and container 30 the oil-solvent mix is cooled to a temperature of from 0 C. to around 30 C. or higher, if desired, to produce phase separation of the oil-solvent system. The cooling coil 28 may be supplemented by the cooling coil 3|, if necessary, or other suitable cooling arrangement.

At a temperature of approximately 0 C. the oil retains the solvent in an amount of only approximately 15 per cent of its volume, and at 30 C. the oil retains about 50 per cent of the solvent by volume, so that, in any case, a portion of the solvent is returned by conduits 32 and 33, controlled by valves 34 and 35 respectively, to the solvent container ill for reuse in the processing system. Ihe non-separated oil-solvent mix is conveyed by conduit 36, controlled by valve 3?, through a container 38, adapted to be heated to the boiling points of the hexafluoroxylene solvent mix by heating coil 39, and thence by conduit 40 into an evaporator 4!. At the boiling point of the hexafiuoroxylene, or slightly above, the oil is freed from solvent and is drained from evaporator 4| by way of conduit 42, controlled by valve 53, into any suitable receptacle or retainer (not shown). The evaporated solvent passes through conduit M and condenser 45 into a collector 46. From the collector 46 the liquid solvent is conveyed by conduit 41 back into solvent container 10. A suitable and conventional pressure equaliz ing valve 48, or other valve system, may be utilized to control the return of solvent to the processing system.

Due to retention by the solvent of a slight oil content, a small fraction of the solvent containing oil is continuously or periodically withdrawn from conduit 32 by way of by-pass conduit 69, controlled by valve 50, into the oil-solvent pas= sageway 35 and freed from the oil content by heating in the manner described.

Alternatively, in an operative arrangement for recycling the solvent, an evacuating pump may be provided in conjunction with the solvent separating vessel 39 and condenser 45, whereby, upon reduction of temperature to about 0 C. or lower, all or substantially all the solvent is withdrawn from the oil dependent upon the extent of evacuation and temperature reduction. Similarly, an evacuating pump or unit can be utilized with the illustrated evaporating process to reduce the heat input to the evaporator. In any case, the particular efiieiency of solvent removal will depend upon the process employed and, if necessary, any remaining solvent may be eliminated from the finished oil products of the process by conventional heating to the boiling point of solvents. In this arrangement the oil product of the process may be removed from the solvent-oil separator as by appropriate conduit means. Further suitable apparatus for separation of solvent from carryover by the asphalt may be included in the system. Such separation may be efiected by vaporization or filtering.

Generally the fluid flows are by gravity and pressure, although when desirable or necessary, suitable and conventional pumps may be utilized at any point or points in the system for transferring the asphalt, oil and solvent as components or in any form of admixture.

In their general application to asphaltic and distillation residues from Mid-Continent, Texas, Mexico and other oil stocks, including shale oil residue bituminous residue or extracts, the proportion of hexafluoroxylene or isomers of hexafiuoroxylene in mixed form to the oil which contains asphaltic constituents bears a relationship which will be peculiar to the stock undergoing deasphaltizing, as heretofore explained.

In the processing of oils and oil stocks residues with hexafiuoroxylene the solvent is a solvent selective to molecular weight of solutes to eifect separation of constituents, which were heretofore separable only incompletely or with considerable difiiculty by distillation or less advantageous extraction processes. This solvent has a low vapor pressure and does not require the equipment to withstand high pressure. This solvent will burn only with great difficulty and, if a fire should occur, the flame will extinguish spontaneously when without support. As an additional advantage in deasphaltizing petroleum oils and asphaltic or distillation residues this solvent is miscible with the oil and crystalline or amorphous microcrystalline wax material at elevated temperatures, leaving an amorphous asphaltic and resinous residue, by reason of its selectivity to molecular weights of solutes at appropriate temperatures and within limits of dilution from about 100% to over 300%. The constituents of the oil and the separate oil phases remaining after the separation of the asphaltic resinous phase are completely or substantially miscible and no separation occurs at either the elevated or reduced temperatures.

Having thus described a new deasphaltizing solvent and its improved method of application for deasphaltizing oils and oil stock residues, I wish it to be understood that changes and modifications of the particular conditions and arrangements set forth will readily occur to the expert without departing from the spirit of my invention, which changes and modifications thus fall within the scope of my invention. I thus define my invention by the appended claims.

What I claim is:

1. A process of removing asphaltic-resinous constituents from petroleum oils and oil containing distillation residues comprising mixing the oil containing material with hexaflu0roxylene, heating the mixture to a range of from about C. to 120 C. and separating the asphaltic-resinous constituents.

2. The process of deasphaltizing and recoveringoil from petroleum oils and asphaltic oil stock residues with hexafluoroxylene solvent material comprising mixing the oil containing material with the said solvent, heating the mixture to a temperature on the order of from 60 C. to 120 C. until the asphaltic phase separates from the liquid solvent-oil phase, separating the asphalt from the liquid phase, cooling the liquid phase, and separating the solvent from the oil.

3, The method of separating asphaltic-resin ous constituents from petroleum oils and oil stock residues with a hexafiuoroxylene solvent of particular selectivity to asphalt and changing seiectivity to oil at difierent temperatures, comprising mixing the hexafiuoroxylene solvent with the oil containing material in the proportion of from about to about 300% parts by volume of solvent, heating the mixture to substantially from 60 C. to C., and separating the asphaltic-resinous constituents as semi-solids.

a. The process according to claim 2, wherein the step of cooling said liquid phase includes the lowering of the temperature thereof to below 60 C.

5. The process according to claim 2, wherein the step of cooling said liquid phase includes the lowering of the temperature thereof to between about 0 C. and about 30 C.

6. The process according to claim 1, wherein said oil containing material and said hexafluoroxylene are heated prior to mixing. I

KARL A. FISCHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,081,720 Van Dijcl: May 25, 1937 2,136,767 Terres et a1 Nov. 15, 1938 2,162,682 Terres et al June 13, 1939 2,188,012 Pilat et a1 Jan. 23, 1940 2,213,798 Anne Sept. 3, 1940 2,478,472 Edwards et a1. Aug. 9, 1949 

1. A PROCESS OF REMOVING ASPHALTIC-RESINOUS CONSTITUENTS FROM PETROLEUM OILS AND OIL CONTAINING DISTILLATION RESIDUES COMPRISING MIXING THE OIL CONTAINING MATERIAL WITH HEXAFLUOROXYLENE, HEATING THE MIXTURE TO A RANGE OF FROM 